#include <iostream>
#include<math.h>
using namespace std;
class Circle{
public:
    Circle()
    :ridus(0)
    {}
    Circle(double r)
    :ridus(r)
    {}
    double getArea(){
        return 3.14 *ridus*ridus;
    }
    double getPerimeter(){
        return 2 * 3.14 * ridus;
    }
    void show(){
        double Area = getArea();
        double Perimeter = getPerimeter();
       cout<<"半径: "<<ridus<<endl;
       cout<<"周长："<<Perimeter<<endl;
       cout<<"面积："<< Area<<endl;
    }

private:
    double ridus;
};
void test(){
   Circle c;
   Circle c2(5);
   c.show();
   c2.show();
}
int main()
{
    test();
    return 0;
}

